The standard component for length measurement used for the conventional electron-beam metrology has used a diffraction grating fabricated by laser interferometer lithography and anisotropic chemical etching on a semiconductor substrate having a surface of plane direction of the (110) plane. A calibration method of it is performed by diffraction angle measurement of the diffraction grating using laser light (for example, see Japanese Patent Application Laid-Open No. 7-71947).
The minimum dimension that is achievable with above-mentioned conventional standard component depends on a resolution limit of the laser interferometer lithography method; one half of a wavelength of the laser light used is the limit of a pitch dimension. With the use of an Ar ion laser of a wavelength of 351.1 nm currently used in the laser interferometer lithography equipment, a pitch dimension of about 200 nm is the limit. On the other hand, exposure equipment in which the laser light source is changed to a short wavelength light source has many technical problems and its development is difficult. At the same time, diffraction angle measurement of a diffraction grating using laser light used for calibration has also a measurement limit; for the minimum pitch dimension of about 200 nm or less, measurement is difficult.
However, since miniaturization of the semiconductor device has been accelerated, the minimum processing dimension is breaking 100 nm. In order to control dimensions of this fine processing, the electron-beam metrology system is being used, and in order to manage absolute precision of this system, a dimensional standard component is indispensable. However, the conventional dimensional standard component is becoming unable to support the minimum processing dimension of the latest semiconductor devices.
In addition, diffraction grating patterning using the laser interferometer lithography method can basically produce only simple line-and-space patterns. For this reason, the same pattern is rendered over the whole surface of the sample, and consequently automatic defining of the position cannot be done for samples in which no alignment mark is used. Therefore, it is not possible to specify exactly which diffraction grating pattern was used at the time of calibration of the metrology system. In the case of the electron-beam metrology system, contamination adhesion associated with beam irradiation causes variation in dimensions of a sample. If the automatic alignment is impossible, it is necessary to perform calibration through the mediation of a human operator, and so automatic calibration cannot be performed.